Vehicle seat

ABSTRACT

A seat back of a vehicle seat includes a side frame member, an upper frame member, and a lower frame member. A headrest has a headrest main body and a frame. The frame has a stay portion and an inner portion. A line of intersection between a first plane and a second plane is positioned farther forward than the upper frame member, and a first angle is less than a second angle. The first plane is an extended plane of a front surface of an upper portion of the inner portion, and the second plane is a plane that contacts front surfaces of the upper frame member and the lower frame member. The first angle is an angle between the first and the second planes, and the second angle is an angle between a center line of a neck and a torso line of a dummy seated in the seat.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2009-252829 filed on Nov. 4, 2009 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a vehicle seat mounted in a vehicle such as an automobile.

2. Description of the Related Art

A vehicle seat typically has a seat back and a headrest. The seat back and the headrest each have a frame and a pad that is attached to the frame. The seat back and the headrest conventionally have various shapes. For example, Published Japanese Translation of PCT application No. 2007-507389 (JP-A-2007-507389) describes a seat back and headrest in which the back distance between the frame of the seat back and the back of the user is substantially the same as the head distance between the frame of the headrest and the head of the user. As a result, when the vehicle is struck from behind (i.e., during a rear impact), the head and torso of the user are restrained at substantially the same instant by the frame of the seat back and the frame of the headrest, so it can be suppressed that the user suffers whiplash.

SUMMARY OF INVENTION

However, there is still a need for a vehicle seat capable of mitigating whiplash to the user. Therefore, this invention provides a vehicle seat capable of more effectively mitigating whiplash to the user.

According to a first aspect of the invention, a seat back has a side frame member that extends vertically at both side portions, an upper frame member that extends in the width direction at an upper portion and connects the side frame members together, and a lower frame member that extends in the width direction at a lower portion and connects the side frame members together. A headrest has a headrest main body and a frame. The frame has a stay portion that extends from the headrest main body and is retained by the upper frame member, and an inner portion that is arranged inside the headrest main body. The inner portion is structured such that a line of intersection between a first plane and a second plane is positioned farther forward than the upper frame member, and a first angle is less than a second angle. The first plane is an extended plane of a front surface of an upper portion of the inner portion. The second plane is a plane that contacts a front surface of the upper frame member and a front surface of the lower frame member. The first angle is an angle between the first plane and the second plane. The second angle is an angle between a center line of a neck and a torso line of a dummy seated in the seat.

During a rear impact, the user moves substantially horizontally (toward the rear) relative to the seat due to inertia force. In the first aspect of the invention, the line of intersection between the first plane and the second plane is positioned farther forward than the upper frame member. Accordingly, the upper portion of the frame of the headrest is positioned farther forward than the upper frame member. Therefore, during a rear impact, first the movement of the head is restrained by the upper portion of the frame of the headrest. Then, the frame is pushed back by the head, and tilts backward with respect to the seat back. As a result, the first angle increases.

At the same time, the frame is structured such that the first angle is less than the second angle. Therefore, the first angle of the frame with respect to the seat back approaches the second angle. Thus, even if the frame is tilted backward with respect to the seat back, the head is still able to be inhibited from falling backward with respect to the torso (i.e., the torso line). Hence, the difference in the angle of the head of the user with respect to the torso before and after a rear impact is less, so whiplash to the user is able to be inhibited.

BRIEF DESCRIPTION OF DRAWINGS

The features, advantages, and technical and industrial significance of this invention will be described in the following detailed description of example embodiments of the invention with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a perspective view of a vehicle seat;

FIG. 2 is a perspective view of the vehicle seat and a first dummy;

FIG. 3 is a left side view of a portion of the vehicle seat and the first dummy;

FIG. 4 is a left side view of a portion of the vehicle seat and a second dummy;

FIG. 5 is a left side view of a portion of the vehicle seat and the second dummy during a rear impact; and

FIG. 6 is a left side view of a portion of the vehicle seat and the second dummy during a high rear impact.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the invention will now be described with reference to FIGS. 1 to 6. As shown in FIG. 1, a seat 1 has a seat cushion 2, a seat back 3, and a headrest 4. The seat cushion 2, the seat back 3, and the headrest 4 each have a frame 2 a to 4 a, a pad 2 b to 4 b, and a cover 2 c to 4 c. The pads 2 b to 4 b are each formed of an elastic member and are attached to the frame 2 a to 4 a. The covers 2 c to 4 c are attached to the surfaces of the pads 2 b to 4 b.

The seat cushion 2 is mounted to the floor 15 of a vehicle such as an automobile via slide rails 5, as shown in FIG. 1. These slide rails 5 retain the seat cushion 2 in a manner such that the position of the seat cushion 2 can be adjusted in the front-rear direction with respect to the floor 15. The seat back 3 is attached to a rear portion of the seat cushion 2 via a reclining device 6 and is able to be placed in an upright position with respect to the seat cushion 2. The reclining device 6 pivotally attaches the seat back 3 to the seat cushion 2 and retains the seat back 3 in such a manner that the angle of the seat back 3 with respect to the seat cushion 2 can be adjusted.

A frame 3 a of the seat back 3 has side panels 3 a 2, an upper pipe 3 a 1, and a lower frame member 3 a 3, as shown in FIG. 1. The lower frame member 3 a 3 is pipe-shaped and extends in the width direction at the lower portion of the seat back 3. The lower frame member 3 a 3 is positioned at the rotational axis of the seat back 3 with respect to the seat cushion 2. The side panels 3 a 2 are sheet-shaped and extend in the vertical direction at the lower portions of both side portions of the seat back 3.

Therefore, the side panels 3 a 2 form the lower portions of side frame members 3 a 5 that extend vertically at both side portions of the seat back 3.

The upper pipe 3 a 1 has left and right upright portions 3 a 11 and a connecting portion 3 a 12 that are integrated with each other, as shown in FIG. 1. The upright portions 3 a 11 extend upward from the upper end portions of the side panels 3 a 2. Accordingly, the upright portions 3 a 11 form the upper portions of the side frame members 3 a 5. The connecting portion 3 a 12 extends in the width direction at the upper portion of the seat back 3 and connects the upper end portions of the pair of upright portions 3 a 11. Therefore, the connecting portion 3 a 12 forms an upper frame member 3 a 4 that extends in the width direction at the upper portion of the seat back 3. A pair of retaining portions 3 e are fixed to the upper frame member 3 a 4, and the headrest 4 is mounted to these retaining portions 3 e.

The headrest 4 is mounted to the upper portion of the seat back 3, as shown in FIGS. 1 and 3. A frame 4 a of the headrest 4 is pipe-shaped and has a pair of stay portions 4 a 1 and an inner portion 4 a 5 that are integrated with each other. The stay portions 4 a 1 extend downward from the headrest main body and are retained by the retaining portions 3 e. The inner portion 4 a 5 is arranged inside the headrest main body and has inclined portions 4 a 2, upper portions 4 a 3, and a connecting portion 4 a 4. The inclined portions 4 a 2 extend upward and forward from the upper end portions of the stay portions 4 a 1. The upper portions 4 a 3 extend upward and forward in a substantially straight line from the upper end portions of the inclined portions 4 a 2. The connecting portion 4 a 4 extends in the width direction along the upper portion of the headrest 4, and connects the upper end portions of the pair of upper portions 4 a 3.

As shown in FIGS. 2 and 3, a first dummy 10 is placed in the seat 1 in order to measure the shape of the seat 1. The first dummy 10 is formed of an H-point device (SAE 3-dimensional H-point machine) 11 and a head restraint measuring device (HRMD) 12. The H-point device 11 is a 3-dimensional manikin for measuring the H-point (hip point) 11 a and the torso angle 11 c.

As shown in FIG. 3, the H-point 11 a is the center of rotation between the waist and the thighs of the first dummy 10. The torso angle 11 c is the angle between a torso line 11 b and a vertical line that passes through the H-point 11 a of the first dummy 10. The torso line 11 b is the center line when the first dummy 10 is placed in the farthest back position. When measuring the shape of the seat 1, the rearward reclining angle of the seat back 3 is adjusted so that the torso angle 11 c is a predetermined angle. This predetermined torso angle 11 c is an angle from 10° to 35° (e.g., 25°±1° that is set according to the evaluation standards (such as E-NCAP) and laws or the like of each country, for example.

The HRMD 12 is a device for measuring the position of the headrest 4, as shown in FIGS. 2 and 3, and is made by ICBC, for example. This HRMD 12 has a head 12 a, probes 12 b and 12 c that are attached to the head 12 a, and a neck 12 d that extends downward from the head 12 a and attaches to the H-point device 11. The height of the head 12 a is determined using, for example, a 50th percentile adult male as the reference. Accordingly, the position of the head 12 a with respect to the H-point 11 a is determined. The probe 12 c is an instrument that measures the height of the headrest 4. The height of the headrest 4 is measured by the distance between the probe 12 c and the top of the headrest 4.

The probe 12 b is an instrument that measures the setback (i.e., a first distance 20 a), as shown in FIG. 3. The setback is the horizontal distance between the back surface of the head 12 a and the front surface of the headrest 4. The setback can be measured by moving the rear portion 12 a 1 of the head 12 a horizontally until it abuts against a front surface first portion 4 d of the headrest 4, and measuring that horizontal movement distance.

As shown in FIG. 3, the side frame members 3 a 5 of the seat back 3 are formed such that the front end edge of each side frame member 3 a 5 is a predetermined second distance 20 b away from the torso line 11 b at one predetermined position, a predetermined third distance 20 c away from the torso line 11 b at another predetermined position, and a predetermined fourth distance 20 d away from the torso line 11 b at yet another predetermined position. The second distance 20 b is a horizontal distance (i.e., a distance in the front-rear direction) between the front surface first portion 4 d of the headrest 4 and a front surface of the upper frame member 3 a 4 that is located farther to the rear than the front surface first portion 4 d. Preferably, the second distance 20 b is greater than the first distance 20 a, and even more preferably, the first distance 20 a+120 mm is greater than the second distance 20 b, and the second distance 20 b is greater than the first distance 20 a+15 mm.

The third distance 20 c is a horizontal distance between the H-point 11 a and the front end edge of the side frame member 3 a 5, as shown in FIG. 3. Preferably, the first distance 20 a+120 mm is greater than the third distance 20 c, and the third distance 20 c is greater than the first distance 20 a+15 mm. The fourth distance 20 d is the horizontal distance between a waist height position of the torso line 11 b and the front end edge of the side frame member 3 a 5. Preferably, the first distance 20 a+120 mm is greater than the fourth distance 20 d, and the fourth distance 20 d is greater than the first distance 20 a+15 mm. The waist height is a height 150±100 mm (such as 200 mm) above the H-point 11 a.

The side frame member 3 a 5 is formed such that the front end edge is positioned between a first line 22 a and a second line 22 b, as shown in FIG. 3. The first line 22 a is a line that connects the center of the upper frame member 3 a 4 with the center of the lower frame member 3 a 3. The second line 22 b is a line that connects a second reference position 21 b with a fourth reference position 21 d and a third reference position 21 c.

The second reference position 21 b is positioned at the same height as the upper frame member 3 a 4 and is the first distance 20 a+15 mm behind the front surface first portion 4 d of the headrest 4, as shown in FIG. 3. The fourth reference position 21 d is positioned the first distance 20 a+15 mm behind the waist height position of the torso line 11 b. The third reference position 21 c is positioned the first distance 20 a+15 mm behind the H-point 11 a.

The rear end edge of each side frame member 3 a 5 is bow-shaped with a concave portion 3 a 7 formed in the center portion, as shown in FIG. 3. The concave portion 3 a 7 curves forward in front of the first line 22 a. Therefore, this concave portion 3 a 7 provides more space behind the seat 1. The space behind the seat 1 provided by the concave portion 3 a 7 increases with a thinner seat back 3.

The frame 4 a of the headrest 4 is formed such that a line of intersection 23 c between a first plane 23 a and a second plane 23 b is positioned farther forward than the upper frame member 3 a 4, as shown in FIG. 3. The first plane 23 a is an extended plane of the front surface of the upper portion 4 a 3. The second plane 23 b is a plane that contacts the front surface of the upper frame member 3 a 4 and the front surface of the lower frame member 3 a 3. The structure of the frame 4 a is preferably such that the line of intersection 23 c is positioned 5 to 100 mm in front of the upper frame member 3 a 4 and the retaining portion 3 e.

Also, the frame 4 a is structured such that a first angle 23 d is less than a second angle 23 e, as shown in FIG. 3. The first angle 23 d is the angle between the first plane 23 a and the second plane 23 b. The second angle 23 e is the angle between the center line of the neck 12 d and the torso line 11 b of the first dummy 10 seated in the seat 1. The frame 4 a is preferably structured such that the first angle 23 d is 5 to 30° less than the second angle 23 e.

As shown in FIGS. 1 and 4, a plurality (such as two) of wires 3 d are provided between the upper frame member 3 a 4 and the lower frame member 3 a 3. These wires 3 d are elastically deformable metal rods that elastically support the back surface of the pad 3 b. Wire lower portions 3 d 1 are fixed by welding or the like to the surface of the lower frame member 3 a 3 and are positioned forward of the center of the lower frame member 3 a 3. Wire upper portions 3 d 4 are fixed by welding or the like to the surface of the upper frame member 3 a 4 and are positioned forward of the center of the upper frame member 3 a 4.

The wires 3 d each have a wire main body 3 d 3 that extends between the lower frame member 3 a 3 and the upper frame member 3 a 4, as shown in FIGS. 1 and 4. Each wire main body 3 d 3 has a rearward extending portion 3 d 2 that extends toward the rear near the wire lower portion 3 d 1.

When performing a rear impact test (i.e., a test when subjecting a vehicle to an impact from behind), a second dummy 13 shown in FIG. 4, instead of the first dummy 10 shown in FIG. 3, is placed in the seat 1. This second dummy 13 is a BioRID-II, for example, and has a torso 13 b and a head 13 c. The torso 13 b has an H-point 13 a, and this H-point 13 a is aligned with the H-point 11 a shown in FIG. 3.

The head 13 c is attached to the torso 13 b via a neck 13 d, as shown in FIG. 4. The head 13 c is placed such that the distance between the rear surface of the head 13 c and the front surface of the headrest 4 is a placement distance 20 e. This placement distance 20 e is set to the first distance 20 a+15 mm, taking into account the posture and the like of the user. Accordingly, the posture and position of the second dummy 13 with respect to the seat 1 is set.

During a rear impact, inertia force causes the second dummy 13 to move substantially horizontally (rearward) relative to the seat 1, as shown in FIGS. 4 and 5. The head 13 c moves from an initial position in front of the headrest 4 toward the front surface of the headrest 4 and strikes the front surface of the headrest 4. The head 13 c closely contacts the frame 4 a while deforming the pad 4 b. The torso 13 b moves from an initial position in which a portion of the torso 13 b is against seat back 3 toward the rear with respect to the seat back 3 while deforming the pad 3 b.

When the vehicle is struck from the rear with even greater force, movement of the head 13 c is restrained by the upper portions 4 a 3 and the connecting portion 4 a 4 of the frame 4 a, as shown in FIGS. 5 and 6. Beyond this, the frame 4 a deforms as it is pushed by the head 13 c. Movement of the upper portion of the torso 13 b is restrained by the upper frame member 3 a 4. Beyond this, the upper frame member 3 a 4 is pushed by the torso 13 b and the side frame members 3 a 5 deform.

Movement of the waist and the buttocks of the torso 13 b is restricted by the side frame members 3 a 5. More specifically, the torso 13 b moves while deforming the pad 3 b and the cover 3 c of the seat back 3 arranged between the side frame members 3 a 5. Then when the center line (i.e., a line corresponding to the spine) of the waist and buttocks goes beyond the front end edges of the side frame members 3 a 5 and moves between the side frame members 3 a 5, the movement of the waist and buttocks is forcibly restricted by the side frame members 3 a 5 via the pad 3 b and the cover 3 c. Beyond this, the side frame members 3 a 5 are able to deform.

The frames 3 a and 4 a are structured such that the first distance 20 a to the fourth distance 20 d have the relationship described above, as shown in FIG. 3. Therefore, during a rear impact, the head 13 c strikes the headrest 4 first. Then the movement of the upper portion of the torso 13 b is restrained by the upper frame member 3 a 4, and the waist and buttocks of the torso 13 b are restricted by the side frame members 3 a 5 and the pad 3 b working together.

The line of intersection 23 c is positioned farther forward than the upper frame member 3 a 4, as shown in FIG. 3. Accordingly, the upper portion 4 a 3 of the frame 4 a is positioned farther forward than the upper frame member 3 a 4. Therefore, during a rear impact, the movement of the head 13 c is restrained by the upper portion 4 a 3 of the frame 4 a. Then, the frame 4 a is pushed back by the head 13 c, and tilts backward with respect to the seat back 3. As a result, the first angle 23 d increases.

The frame 4 a is structured such that the first angle 23 d is less than the second angle 23 e. Therefore, the first angle 23 d of the frame 4 a with respect to the seat back 3 approaches the second angle 23 e. Thus, even if the frame 4 a is tilted backward with respect to the seat back 3, the head 13 c is still able to be inhibited from falling backward with respect to the torso (i.e., the torso line 11 b). Hence, the difference in the angle of the head of the user with respect to the torso before and after a rear impact is less, so whiplash to the user is able to be inhibited (see FIGS. 4 and 6).

As shown in FIG. 3, the upper frame member 3 a 4 and the headrest 4 are structured such that the second distance 20 b is greater than the first distance 20 a. Therefore, the distance between the head of the user seated in the seat 1 and the headrest 4 can be assumed by the first distance 20 a. That is, the head 12 a of the HRMD 12 can be assumed to be the head of the user seated in the seat 1. The distance between the upper portion of the torso of the user and the upper frame member 3 a 4 is determined by the second distance 20 b. That is, the back surface of the upper portion of the torso of the user is substantially equal to the position in the front-rear direction of the front surface first portion 4 d of the headrest 4. Therefore, the second distance 20 b can be assumed to be the distance between the upper frame member 3 a 4 and the back surface of the upper portion of the torso.

During a rear impact, inertia force causes the user to move substantially horizontally (backward).relative to the seat 1. Therefore, the head of the user moves from an initial position in front of the headrest 4 and strikes the front surface of the headrest 4. The torso of the user moves backward from an initial position in which a portion of the torso is against the seat back 3, and that movement is restrained by the upper frame member 3 a 4.

In this example embodiment, the second distance 20 b is greater than the first distance 20 a. Therefore, the movement of the upper portion of the torso can be restrained by the upper frame member 3 a 4 after the head strikes the front surface of the headrest 4. As a result, whiplash to the user can be suppressed. Also, because the second distance 20 b is greater than the first distance 20 a, the structure is able to be simpler than a structure in which the two distances are substantially the same, such as that described in JP-A-2007-507389, for example.

Also, the upper frame member 3 a 4 and the headrest 4 are preferably structured such that the second distance 20 b is greater than the first distance 20 a+15 mm, as shown in FIG. 3. Therefore, during a rear impact, the head of the user is able to reliably strike the headrest 4 before the movement of the upper portion of the torso of the user is restrained by the upper frame member 3 a 4. The reason having the first distance 20 a+15 mm is because the placement distance 20 e shown in FIG. 4 is taken into account. That is, in the rear impact test, the head 13 c of the dummy 13 is placed the first distance 20 a+15 mm in front of the headrest 4 taking into account the seated position of the user and the like. Having the second distance 20 b be greater than the first distance 20 a+15 mm effectively inhibits the head 13 c of the dummy 13 from falling backward with respect to the torso 13 b. This result was able to be confirmed by the rear impact test.

Also, the side frame members 3 a 5 are structured such that the third distance 20 c is greater than the first distance 20 a+15 mm, as shown in FIG. 3. Therefore, the relationship of the distance between the side frame members 3 a 5 and the buttocks of the user can be assumed by the third distance 20 c. That is, the H-point 11 a can be assumed to be the buttocks of the user seated in the seat 1. Also, the structure is such that the third distance 20 c is greater than the first distance 20 a+15 mm, so during a rear impact, movement of the buttocks is forcibly restricted by the side frame members 3 a 5 after the head of the user strikes the front surface of the headrest 4. As a result, the head is inhibited from falling backward with respect to the torso, so whiplash to the user can be suppressed.

Also, the side frame members 3 a 5 are structured such that the fourth distance 20 d is greater than the first distance 20 a+15 mm, as shown in FIG. 3. Therefore, the relationship of the distance between the side frame members 3 a 5 and the waist of the user can be assumed by the fourth distance 20 d. That is, the waist height position of the torso line 11 b can be assumed to be the waist of the user. Also, the structure is such that the fourth distance 20 d is greater than the first distance 20 a+15 mm, so during a rear impact, movement of the waist is forcibly restricted by the side frame members 3 a 5 after the head of the user strikes the front surface of the headrest 4. As a result, the head is inhibited from falling backward with respect to the torso, so whiplash to the user can be suppressed.

Also, the front end edges of the side frame members 3 a 5 are positioned in front of the first line 22 a and behind the second line 22 b, as shown in FIG. 3. Therefore, during a rear impact, the head of the user strikes the headrest 4 first. Then the movement of the upper portion of the torso of the user is restrained by the upper frame member 3 a 4, and movement of the buttocks and waist is restricted by the side frame members 3 a 5.

Also, the upper portions 4 a 3 of the frame 4 a are structured such that the first angle 23 d is less than the second angle 23 e−5°, as shown in FIG. 3. Therefore, even if the frame 4 a is tilted 5° back with respect to the seat back 3, the neck of the user can still be inhibited from falling backward with respect to the torso. Thus, it can be preferably suppressed that the user suffers whiplash.

During a rear impact, inertia force causes the weight of the user to be applied to the seat back 3. On the other hand, the wire lower portions 3 d 1 are attached to the lower frame member 3 a 3 at locations on the front side with respect to the center of the lower frame member 3 a 3 from the side view, and the wire upper portions 3 d 4 are attached to the upper frame member 3 a 4 at locations on the front side with respect to the center of the upper frame member 3 a 4 from the side view, as shown in FIG. 4. Therefore, when force from the pad 3 b is applied from the front toward the rear to the wire lower portions 3 d 1 and the wire upper portions 3 d 4, the wire lower portions 3 d 1 and the wire upper portions 3 d 4 are pushed against the lower frame member 3 a 3 and the upper frame member 3 d 4, respectively, and are thus able to be inhibited from detaching from the lower frame member 3 a 3 and the upper frame member 3 a 4.

Also, the wires 3 d have the rearward extending portions 3 d 2, as shown in FIG. 4. Therefore, during a rear impact, movement of the torso of the user toward the seat back 3 side tends not to be impeded by the wires 3 d, so the torso of the user moves smoothly toward the seat back 3 side. Thus, whiplash to the user that may occur due to the movement of the torso being restricted before the head is restrained can be suppressed.

Moreover, the rearward extending portions 3 d 2 of the wires 3 d extend behind the first line 22 a, as shown in FIG. 4, so the wire main bodies 3 d 3 are positioned sufficiently behind the upper frame member 3 a 4 and the lower frame member 3 a 3. As a result, during a rear impact, the user is able to reliably move backward with respect to the seat back 3, without being impeded by the wires 3 d.

MODIFIED EXAMPLES

The invention is not limited to the example embodiments described above, but may also be carried out in other modes such as those described below.

(1) The upper frame member 3 a 4 of the seat back 3 shown in FIG. 1 is pipe-shaped, but it may also be plate-shaped or the like.

(2) The inner portion 4 a 5 of the headrest 4 shown in FIG. 1 is pipe-shaped, but it may also be plate-shaped or the like.

(3) The upper portion 4 a 3 of the headrest 4 shown in FIG. 3 is straight, but it may also be curved. The first plane 23 a when the upper portion is curved may be determined by a plane that passes through the front surface at the uppermost portion of the upper portion and the foremost surface of the upper portion.

(4) The wires 3 d shown in FIG. 4 have the rearward extending portions 3 d 2 that extend curving backward near the wire lower portions 3 d 1. However, the wires may also have rearward extending portions that extend curving backward near the center portions of the wire main bodies or near the wire upper portions. Alternatively, the wire main bodies may be bow-shaped, and rearward extending portions may be formed along substantially the entire length of the wire main bodies.

(5) The seat 1 shown in FIG. 1 is mounted in a vehicle such as an automobile, but it may also be mounted in a marine vessel or an aircraft or the like. 

What is claimed is:
 1. A vehicle seat comprising: a seat cushion; a seat back that stands upright with respect to the seat cushion; and a headrest that attaches to an upper portion of the seat back, the seat back including: a side frame member that extends vertically at opposed side portions of the seat back, an upper frame member that extends in a width direction of the seat back at an upper portion of the seat back and connects the side frame members together, a lower frame member that extends in the width direction at a lower portion of the seat back along a rotational axis of the seat back and connects the side frame members together, and a plurality of wires disposed between each side frame member that extend in a height direction from the upper frame member to the lower frame member in an angled manner such that a distance between the plurality of wires gradually narrows toward the lower frame member, the plurality of wires extending from the lower frame member at a position forward of a center of the lower frame member and the rotational axis of the seat back, wherein a concave portion that curves forward in a front-rear direction of the vehicle seat in front of a first line that connects a center of the upper frame member of the seat back and the center of the lower frame member of the seat back together is provided on a rear end edge of the side frame member, and each of the plurality of wires includes a wire lower portion, a wire upper portion, and a wire main body, the wire main body including a rearward extending portion that connects the wire main body to the wire lower portion, and the headrest including: a headrest main body, and a frame, the frame having: a stay portion that extends from the headrest main body and is retained by the upper frame member of the seat back, and an inner portion that is arranged inside the headrest main body, the inner portion being configured such that a line of intersection between a first plane and a second plane is positioned farther forward in the front-rear direction of the vehicle seat than the upper frame member, the first plane being an extended plane of a front surface of an upper portion of the inner portion of the frame of the headrest, and the second plane being a plane that extends between a front surface of the upper frame member of the seat back and a front surface of the lower frame member of the seat back, the first plane and the second plane being configured to define a first angle therebetween, and when a dummy is seated in the seat, the first angle is configured to be less than a second angle defined by a center line of a neck and a torso line of the dummy.
 2. The vehicle seat according to claim 1, wherein the inner portion of the frame of the headrest is configured such that the first angle is less than the second angle minus 5°.
 3. The vehicle seat according to claim 1, wherein a first horizontal distance is defined between a back surface of a head of the dummy to be seated in the vehicle and a front surface of the headrest in the front-rear direction, wherein a second horizontal distance is defined between the front surface of the headrest and the front surface of the upper frame member that is located rearwardly of the front surface of the headrest, wherein a third horizontal distance is defined between a hip point of the dummy to be seated in the vehicle seat and a front end edge of the side frame member, and wherein a fourth horizontal distance is defined between a waist height position of the torso line of the dummy to be seated in the vehicle seat and the front end edge of the side frame member.
 4. The vehicle seat according to claim 3, wherein the second horizontal distance is greater than the first horizontal distance such that during a rear impact, the head of the dummy to be seated in the vehicle seat strikes the front surface of the headrest before the torso of the dummy is restrained by the upper frame member of the seat back, thereby suppressing a whiplash to the dummy to be seated in the vehicle seat.
 5. The vehicle seat according to claim 3, wherein the third horizontal distance is greater than the first horizontal distance plus 15 mm such that during a rear impact, movement of a buttocks region of the dummy to be seated in the vehicle seat is restricted after the head of the dummy to be seated in the vehicle seat strikes the front surface of the headrest thereby suppressing a whiplash to the dummy to be seated in the vehicle seat.
 6. The vehicle seat according to claim 3, wherein the fourth horizontal distance is greater than the first horizontal distance plus 15 mm such that during a rear impact, movement of a waist region of the dummy to be seated in the vehicle seat is restricted after the head of the dummy to be seated in the vehicle seat strikes the front surface of the headrest thereby suppressing a whiplash to the dummy to be seated in the vehicle seat.
 7. The vehicle seat according to claim 3, wherein the front end edge of each side frame member is positioned in front of the first line and behind a second line that extends along a length of each side frame member between a first reference point positioned at a height of the upper frame member and a second reference point positioned at a height of the torso line such that a movement of an upper portion of the torso of the dummy to be seated in the vehicle seat is restrained by the upper frame member, and movement of a buttocks region and a waist region is restricted by each side frame member.
 8. The vehicle seat according to claim 1, wherein the wire lower portion is provided at the lower frame member at the position forward of the center of the lower frame member and the rotational axis of the seat back, and wherein the wire upper portion is provided at the upper frame member at a position forward of the center of the upper frame member.
 9. The vehicle seat according to claim 1, wherein the rearward extending portion extends behind the first line such that the wire main body is at least partially disposed behind the upper frame member and the lower frame member. 